Yorkshire Pup AKC Genetic Issues please help Collapsed Tracheal

My pup was flown in from Ohio to Reno Nevada on March 30th and two or three days later I complained that my yorkie had a cough that wasn't normal. This dog was sold to me buy a broker who sells dogs for breeders which wasn't great, however he told me he didn't have it when he left which I thought was garbage. I research kennel cough and everything alike. My dog on the 10th day of being home started coughing worse and couldn't breath. I took him to the vet and because he seemed to be somewhat active I was given Clavamox. It didn't seem to help and a few weeks later it the coughing came back stronger. Again and again the seller told me he's fine. My dog is coughing like a goose, coughs when he is excited or eats, all the same symptoms of a collapsed tracheal issue which is genetic. I've already spent $100 at the vets for just Clavamox. The x-ray will cost $135 if I take him in this week, plus vet fee. My question is if he does have this issue how can I go after the seller and breeder?

you cant - there is absolutely nothing you can do.

pure bred dogs have health and genetic problems just like any other dog... in fact, some have more because the gene pool is smaller.

unless your breeder/seller showed you evidence (which would have been fake documentation) to show that those pups did not have that genetic trait before you bought them (which would have made the dog EXTREMELY expensive).

OR

unless you can show evidence that the breeder/seller knew without a doubt that the dog had this particular problem BEFORE they sold it to you without telling you, then you cant do a thing.